There are numerous apparatuses and methods which have been disclosed that provide for the grinding, polishing and burnishing of workpieces. These apparatuses and methods permit such work to be performed on workpieces which are both stationary and moving. Examples of such apparatuses and methods are grinding centers, as well as the more conventional grinding machines, and the methods in which they are used.
While useful for their purposes, the use of such apparatuses and methods for working on stationary workpieces presents particular problems. Specifically, where stationary workpieces are involved, internal residual stresses can build-up in the workpieces that are generated by the working tool (i.e., a grinding wheel). These internal residual stresses can, in turn, result in a flow, or other deformation, of the material in the workpiece. Such deformed workpieces are useless, resulting in losses of time and material.
A method and apparatus for grinding straight edge cutting tools is disclosed in U.S. Pat. No. 4,984,394 issued to Suzuki et al. The grinder units concurrently grind opposite sides of the workpiece providing the opportunity to introduce internal stresses. Japanese Patent No. 58-177261 issued to Yonezawa discloses multiple wire brushes simultaneously contacting the surface of tubing. Italian Patent No. 511722 discloses working tools movable along parallel axes which do not intersect perpendicularly.
Accordingly, it can be seen that there remains a need for apparatuses and methods for grinding, polishing or burnishing a stationary workpiece which relieve the internal residual stresses in the workpiece which can result in flow or deformation of the material therein during operations thereon.